The combustion system of a gas turbine contains the hot gasses and flame produced during the combustion process and channels the hot gas to the turbine section of the engine. An industrial gas turbine engine commonly has several individual combustion device assemblies arranged in a circular array about the engine shaft. A respective circular array of transition ducts, also known as transition pieces, connects the outflow of each combustion chamber to the inlet of the turbine section. Each transition piece may be a tubular structure that channels the combustion gas between a combustion chamber and the first row of stationary vanes of the turbine section.
The transition piece may include, a tubular inner liner or body that provides a flow path for the combustion gas, which may reach temperatures up to about 1500° C. The liner may be cooled by compressed air diverted from the turbine compressor. An impingement sleeve may surround the inner liner of the transition piece. This provides a dual-wall enclosure for the combustion gas path. The impingement sleeve may include holes that admit the coolant and direct it onto an exterior surface of the inner liner to cool the liner.